Ratchet feed stoker



W 1936. A. B. FISHER M 929 RA'I'CHET FEED STOKER Filed Nov 13, 1934 Patented Apr. 28, 1936 UNITED STATES PATENT OFFICE RATCHET FEED STOKER Application November 13, 1934, Serial No. 752,891

1 Claim.

This invention relates to stokers of the ratchet feed type for coal burning furnaces.

Ratchet feed stokers have been in use for many years and the power units thereof are 5 operated in a bath of oil. Much trouble has been experienced with the pawls of such units which drive the ratchets owing to the fact that when a heavy oil is used for the bath and the temperature drops considerably the oil congeals and prevents the pawl from fully engaging the ratchet. When this happens one of two objectionable things occurs; the pawl is either held above the teeth which prevents the stoker from feeding coal and during which time the fan is operating and the fire burns out; or if the oil is not sumciently congealed to hold the pawl entirely out of the teeth, the pawl is frequently just low enough to catch the tops of the teeth thus shearing them off until both pawl and ratchet have to be replaced.

When thin oil is used and the pawl is made heavy or a spring used to force it into the teeth, then the pawl produces noise on the back stroke over the ratchet teeth. This noise is especially annoying in household, church or apartment house installations.

It is to overcome these objectionable features that this invention is designed and a primary object of the invention is to provide means to 0 ensure the positive engagement of the pawl with the ratchet tooth under all conditions and with oils of various kinds, thereby ensuring continuous feeding of the coal by the stoker.

Another object is to so construct such a stoker feed that the pawl will be caused to drop positively and squarely into the ratchet under all conditions ensuring the constant feeding of the coal without danger of the tops of the teeth being sheared off and without producing any objectionable noises.

Still another object is to provide a feed having a pawl and control disk construction whereby the pawl is forced into the ratchet regardless of how thick the oil may be and which permits the pawl to be made light weight to prevent noise over the teeth of the back stroke.

Another object is to provide a variable feed stoker having a control disk and a pawl with a stop or limit pin carried thereby at a point to cause said pin when it strikes the tapered face of the control disk to force the pawl squarely into the ratchet teeth no matter how thick the oil may be, thus ensuring positive feeding of the coal.

In carrying out these objects the invention is susceptible of modifications without departing from the spirit or sacrificing any of the advantages of the claimed invention.

In the accompanying drawing Figure 1 represents a side elevation of a stoker power unit embodying this invention with one of its gear casing plates broken out to show the interior construction;

Fig. 2 is a transverse vertical section taken on the line 2-2 of Fig. 1;

Fig. 3 is a top plan view thereof; and

Fig. 4 is a detail side elevation of the pawl and a slightly different form of control disk.

In the specific embodiment of the invention illustrated in the accompanying drawing and hereinafter described in detail, the power unit shown as a whole at l includes an oil-tight casing having a removable front plate 2. A worm shaft 3 extends thru the upper part of the casing 1 and is journalled in the opposite ends thereof. The worm 4 of shaft 3 meshes with and is designed to continuously drive a worm gear 5 loosely mounted on a shaft 6 extending transversely thru the casing in a plane at right angles to shaft 3 and having mounted to rotate with said gear a cam 8.

An inverted J-shaped lever 9 is fulcrumed at H! at the bottom of casing I and is located between gear 5 and ratchet l in the path of the periphery of cam 8 to swing back and forth under the action of cam 8 and a coiled push spring [3.

A pawl H is pivoted at the short end of lever 9 and its tooth I2 is arranged to engage the teeth of ratchet wheel 1, and thus rotate the drive shaft 6 and the feed conveyor connected therewith.

A stop or control disk I5 is fixedly mounted on a shaft 16 equipped with an adjustment knob l'l bearing on its face characters to correspond with six peripheral faces a, b, c', d, e, and f on the disk I5 which correspond with the six positions to which the knob Il may be turned.

A laterally extending pin l8 on the hub of pawl ll overlies the periphery of disk [5 so that when this disk is turned by manipulation of knob I! the desired face of disk I5 is brought under pin I8. Disk I5 acts merely as a multiple-faced stop. It will be observed that disk [5 is excentric to its shaft I6. When spring l3 returns the pawlcarrying lever 9, the extent of its return is governed by the face of disk l5 that has been turned to be contacted by pin l8 on the tail of the pawl-dog. When face a of disk is presented in the line of travel of pin I8, the lever 9 is permitted to make its greatest return swing,

face on disk I; therefore pawl I I is swung so far back that when pin I8, on the tail of the pawl,

' strikes the face a of the disk I5 pawl-tooth I2 is forced into the fifth throat reached by it on its return swing and excentric 8 will, therefore, give the ratchet wheel I a five teeth movement when it actuates pawl-carrying-lever 9; face b stops the return of lever 9 and forces the pawl tooth I2 into the fourth ratchet wheel throat and thus limits the rotation of ratchet wheel I to a four teeth movement; face 0 stops the return of lever 9 and forces the pawl tooth I2 into the third ratchet wheel throat and limits the extent of the rotation of the ratchet wheel I by cam 8 swinging lever 9 to a three teeth movement; face d limits the rotation to two teeth; face e limits the return of the pawl and the rotation of the ratchet wheel to one tooth, and face 1 does not permit any return movement of lever arm 9 and the pawl it carries and consequently the machine will then run without any feeding movement, whatever, as long as face ,f is presented to contact with pin I8. It will thus be seen that the disk I5 controls the number of notches the pawl engages by limiting the travel of the pawl arm which is moved by the cam 8.

The above noted objections have been overcome entirely by making the stop or limit pin a part of the pawl and locating it on the pawl at a point so that when it strikes the tapered face of the control disk I5 it forces the pawl into the ratchet regardless of how thick the oil may be and this construction permits the pawl to be made light weight and thereby prevent noise over the teeth on its back stroke.

It will thus be seen that the forcing of the pawl into the ratchet wheel I will turn shaft 6 and ensure the positive feeding of the coal thru the conveyor, not shown, which is connected with said shaft 6.

In operation the shaft 3 carrying the worm 4 is rotated by a motor, not shown, driving the worm gear 5. The cam 8 which rotates with the worm gear causes the outward movement of the lever bar or arm 9, which arm is held in contact with the cam by a push spring I3. This causes a to and fro movement of the lever arm 9 about its fulcrum Ill. The extent of movement of this lever arm 9 is controlled by the control disk I5 and the stop pin I8 carried by the hub of pawl II which is pivoted on the laterally extending short arm of lever 9.

- In Fig. 4 a slightly different form of control disk I 5' is shown the size and arrangement of the inclined faces being different, the pawl II and the pin I8 are however the same.

I claim as my invention:

In a coal feeding stoker having an adjustable stepv by step feeding motion the combination of a casing, a driven shaft mounted in bearings in the casing, aworm fixed upon the driven shaft, a screw conveyor shaft mounted at right angles to the driven shaft in bearings in the casing, a worm wheel in engagement with the worm and mounted to turn freely upon the screw conveyor shaft, a ratchet wheel fixed to the screw conveyor shaft, an excentric cam carried by the worm wheel, a pawl lever pivoted to the casing and mounted to swing in the path of the excentric cam, a spring engaging the casing and the pawl lever for holding the pawl lever in engagement with the face of the excentric cam, a pawl pivoted on the free end of the pawl lever to engage the teeth of the ratchet wheel, a tail on the pawl, a pintle fixed to the casing, a stop having a plurality of faces disposed excentrically rotatably mounted upon the pintle to contact with the tail of the pawl and means to manually rotate the stop to present the desired face to the tail of the pawl whereby the pawl is positively pressed into the desired tooththroat by the contact of the pawl tail and a stop face.

ARTHUR B. FISHER. 

